Looking for help from a old time vacuum tube person

[jtrouter]

Hello
I have a bunch of old tube gear and am always looking for spare 6KV6 tubes.
I have probably 18 of them from most manufactures and NONE of them have a
grid/anode cap on top. Now i found a guy selling a pair but they have the cap on top
and i am confused? They are marked 6KV6A ? Is this a normal way? Should i stay away?
Thank you and look forward to your input.

 

[guitar_199]

No expert by any means... but I'll offer what I found......
My RCA tube manual just shows it as a 9 pin tube and mentions nothing about a cap lead at all. As you have probably already done.... I "Googled" the tube ... and not one picture I found showed a cap lead.

So.... unless that guy just stuck up a "stock photo" of some kind..... I don't know....

 

[guitar_199]

Although...... this link to RF Parts... shows a cap... and even has a comment that "as strip of copper is used to connect the cap the the pin on the base" .... so I guess you can do it either way. I feel a little more solid after seeing it at "RF Parts"....

6KV6A, National, Beam Power Pentode, New old stock, New In Box

6KV6A, National, Beam Power Pentode, New old stock, New In Box

www.rfparts.com

 

[Dmans]

Run away.
Never any luck with "National" brand tubes. I think they are the NTE of the vacuum tube market.

73
David

 

[nomadradio]

I was about to take a pic of the "skunk stripe" tube that Richardson sold a few years back. They had the incentive to find something to sell people that kept asking for 6KV6A tubes. But the well had run dry, and nobody had made that one for years. They found an equivalent that had a plate cap, and slight differences in the pin assignments. They took a 9-pin sweep tube with a plate cap and put a ring of G10 circuit-board material under it, with the nine pins mounted on it. The pins coming out of the glass were soldered to pads on this ring of circuit-board material and cut off short. Foil traces would re-route the pins to match the 6KV6 wiring diagram. The anode (plate) of the 6KV6 is on pin 9. A "skunk stripe" of copper foil made the connection from the plate cap down to pin 9, with a black insulating sleeve glued over the metal plate cap.

We found that this substitute would work in some amplifiers but not in others. Never did find out the original type number that they scraped off before doing the conversion.

The "National" brand has belonged to Richardson Electronics for some time now.

Just looked at the RF Parts listing and that's what they're selling.

73

 

[jtrouter]

I was about to take a pic of the "skunk stripe" tube that Richardson sold a few years back. They had the incentive to find something to sell people that kept asking for 6KV6A tubes. But the well had run dry, and nobody had made that one for years. They found an equivalent that had a plate cap, and slight differences in the pin assignments. They took a 9-pin sweep tube with a plate cap and put a ring of G10 circuit-board material under it, with the nine pins mounted on it. The pins coming out of the glass were soldered to pads on this ring of circuit-board material and cut off short. Foil traces would re-route the pins to match the 6KV6 wiring diagram. The anode (plate) of the 6KV6 is on pin 9. A "skunk stripe" of copper foil made the connection from the plate cap down to pin 9, with a black insulating sleeve glued over the metal plate cap.

We found that this substitute would work in some amplifiers but not in others. Never did find out the original type number that they scraped off before doing the conversion.

The "National" brand has belonged to Richardson Electronics for some time now.

Just looked at the RF Parts listing and that's what they're selling.

73

Thank you! yes that's what they are, I just went and looked close at the picture and that is what they have done. Strange but i think i will skip these. I do have plenty of new ones but always look for spares. As always thanks guys for the fantastic information,

 

[Captain Kilowatt]

Run away.
Never any luck with "National" brand tubes. I think they are the NTE of the vacuum tube market.

73
David

Ran National brand 807's and 833C's for many, many years in several of the Gates BC-1 series broadcast transmitters and although not as good as Cetron, we never really had any issue with them. They would last just as long but instead of a gradual roll-off in performance they would almost avalanche towards their end of service life.

 

[BJ radionut]

Most of the "National" brand tubes were made in Japan...They were made close to RCA/GE type specs. Private labeled some of Radio Shack tubes.